A U.S. drone strike in eastern Afghanistan earlier this week killed Abu Sayed, the leader of the Islamic State’s offshoot there, U.S. officials said Friday.

A Pentagon statement said that other Islamic State members were also killed in the July 11 operation in Konar Province and said that it “will significantly disrupt the terror group’s plans to expand its presence in Afghanistan.” The statement provided little other detail about the strike.

A U.S. official, who spoke on the condition of anonymity to discuss the attack, said it targeted a meeting and that U.S. forces had not been tracking Abu Sayed for long.

If confirmed, Abu Sayed’s death marks another setback for the terrorist group in Afghanistan. U.S. and Afghan forces have been pummeling Islamic State positions in eastern Afghanistan for months in an effort to dislodge the militants from the craggy peaks and remote valleys of Nangahar and Konar provinces. In April, a team of 50 U.S. Army Rangers and 40 Afghan commandos assaulted a hamlet in Achin, a district of Nangahar province, killing Abdul Hasib, Abu Sayed’s predecessor as commander of ISIS in Afghanistan, and roughly 30 other militants. Eight months before Abdul Hasib was killed, Hafiz Saeed Khan, the Islamic State’s leader in Afghanistan before Abdul Hasib, was killed in a U.S. drone strike.

Two U.S. Rangers were killed in the operation to kill Abdul Hasib, the Pentagon said, possibly from “friendly fire.” Seven U.S. service members have died in combat in Afghanistan in 2017, six of them in the eastern part of the country while supporting the fight against the Islamic State.

Just two weeks before the attack on Abdul Hasib, the U.S. military dropped a 22,000-pound bomb, called the MOAB, in Achin, destroying what was described by the military as a key cave complex used by the militants. It is unclear how many fighters, if any, were killed in that operation.

Despite being under constant bombardment and hemorrhaging leadership, the Islamic State’s offshoot in Afghanistan has managed to keep a foothold in the country. In June, the group seized Tora Bora from the Taliban. Once a key battleground between U.S. forces and al-Qaeda, the area — pockmarked with caves and redoubts — is easily defensible from the ground and hard to target from the air.

The Pentagon assesses that the Islamic State presence in Afghanistan is down to less than 1,000 fighters, from a 2015 mark of 2,500. The presence of the group has stretched Afghan forces thin as they have had to divert resources away from fighting the Taliban, the militant group that has fought the U.S.-backed government since it was ousted from power in 2001.

More than 2,000 U.S. troops and tens of thousands of Afghans have died in what has become America’s longest-running war. Secretary of Defense Jim Mattis told lawmakers that the United States is “not winning” there, and he is set to propose a new strategy for the war that could involve sending thousands more troops to Afghanistan. Some NATO countries have already pledged to increase troop levels ahead of any formal U.S. announcement. The increase of forces would bring additional training capabilities to the struggling Afghan military along with fire support to give it more leverage against the revitalized insurgency.